Mayweather started his career at Top Rank, and Trampler matched him in 36 bouts. As the victories piled up, Mayweather and his family and others in the company had more input, but that final blessing from Trampler was always a valued commodity.

Same for Pacquiao, who has fought 22 times under the Top Rank banner, with Trampler affirming career-defining upset victories against Marco Antonio Barrera in 2003 and Oscar De La Hoya in 2008.

Now, Mayweather and Pacquiao are in training for each other, May 2 at MGM Grand in Las Vegas, in a bout that will shatter pay-per-view and live-gate sales records.

“The reason this is a compelling fight is that the fans are making it the biggest fight in history,” Trampler said.

From the local rings in the Philippines to the grand stages in Las Vegas, Manny Pacquiao's journey to become the best boxer in the last decade had twists and turns.

“Yes, there’s the obvious contrasts in styles: Manny is a hard-hitting southpaw, Floyd is a sharp-shooting, slick-boxing right-hander. Plus, it’s universally agreed they’re the two best fighters of their generation.”

Trampler said in the matchup of styles, Pacquiao has an advantage.

“Nobody’s beaten Floyd Mayweather — 47-0, dominated the sport for the last decade — but if you had to design a fighter, a style that could beat [him], you’re going to come up with a left-hander who’s good with lateral movement, side to side, shifty [who] can punch with either hand.

“That’s not a guarantee that Manny’s going to win the fight, but he’s got the best chance of anyone to take away the ‘0’ on Floyd’s record.”

While both fought under the Top Rank Promotions banner, De La Hoya was the true “Golden Boy,” his 1992 Olympics story of earning a gold...

(Lance Pugmire)

When the fight begins, Trampler detailed the telltale indicators of how it’s progressing in who’s favor.

“To beat a left-hander, you want to pressure him and take away his left-handedness. … So if I see Floyd dictating the pace, moving Manny where he wants him, I’m going to say Manny’s going to lose.

“If Manny is aggressive and shows that good lateral movement and throws punches in bunches and gets off first on Floyd, I’m going to pick Manny.

“This is the first guy Floyd has fought … when the bell rings, Manny Pacquiao’s coming out not to beat him but to knock him out and hurt him. That’s his mindset, that’s what he’s telling us. Floyd’s a man. He understands this guy’s coming to hurt him.”

Trampler said Mayweather’s ring savvy is a critical element.

“Floyd knows how to negate everything, how to nullify and neutralize what you’re going to do. His whole life, he was bred to be a fighter. Nobody’s going to do anything to Floyd that he hasn’t seen before, except Manny Pacquiao.”

Arum has always leaned heavily on Trampler’s counsel when it came to pursuing or avoiding a certain fight. What were the cases with Mayweather and Pacquiao?

“Manny Pacquiao has never turned down a guy that we offered him,” Trampler said. “Floyd Mayweather has turned down fights. He’s been very careful and selective in who he fights, and that’s fine. That’s what a smart fighter and manager are supposed to do. Manny will fight anybody.”

While Arum has said Mayweather habitually rejected fast southpaws, Trampler said he “can’t remember” a specific case where that occurred.

Mayweather left Top Rank in 2006.

“Floyd hasn’t ducked anyone,” Trampler said. “He’s proven his value and his worth. He’s the biggest pay-per-view attraction of all time. He knows what he’s doing. He should be promoter of the year.”

The pair actually fought on the same card together once, on Nov. 10, 2001, at Bill Graham Civic Auditorium in San Francisco.

Trampler was there.

Pacquiao, in his second U.S. bout, fought Agapito Sanchez to a draw in a super-bantamweight title unification match and Mayweather successfully defended his super-featherweight belt when Jesus Chavez’s corner threw in the towel after nine rounds.

“We were Floyd’s promoter and very bullish on Floyd. … I told [Top Rank President] Todd duBoef when we signed him, ‘This kid has a chance to be something special,” Trampler said. “Manny was an anonymous guy, a substitute, came from poverty, from the other side of the world.

“Out of nowhere, completely unknown to us, Emmanuel Pacquiao, we’d seen his name in fight results, had no idea who he was … eventually through a series of moves, we ended up with [him] and we’re thrilled by it.”

So who wins?

“Manny Pacquiao is going to win,” Trampler said. “I don’t know if he can stop Floyd, but I think he’s going to outwork him and overwhelm him.”